There has been a known structure including a battery, a protection circuit, and other elements as a unit as disclosed for example by JP-A 2009-152183, according to which a coin type secondary battery is stored in a battery case that has a substrate mounted with circuit components thereon and provided with positive and negative deriving electrodes (external electrodes) formed thereon. In this way, the battery unit having the circuit portion and the coin type secondary battery can be used for a device similarly to a coin type primary battery.